Principle Of Inheritance And Variation Question 48
Question: Assertion : Z-DNA follows a zig-zag course. Reason : Z-DNA is left handed.
Options:
A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B) If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C) If the assertion is true but the reason is false
D) If both the assertion and reason are false
Show Answer
Answer:
Correct Answer: B
Solution:
Z-DNA is left-handed double helix with zig-zag back-bone, alternate purine and pyrimidine bases, single turn of 45 Å length with 12 base pairs and a single groove.
Due to a different arrangement of molecules within Z-DNA polymer, phosphate backbone follows a zig-zag course, while in B-DNA it is regular.
In Z-DNA, sugar residues have alternating orientation so that the repeating unit is a dinucleotide against B-DNA where repeating unit is a mononucleotide and the orientation of sugar molecules is not alternating.
BETA
